code: def get_schema_from_dataset_url(
      dataset_url_or_urls,
      hdfs_driver="libhdfs3",
      storage_options=None,
      filesystem=None,
  ):
      """Returns a :class:`petastorm.unischema.Unischema` object loaded from a dataset specified by a url.
  
      :param dataset_url_or_urls: a url to a parquet directory or a url list (with the same scheme) to parquet files.
      :param hdfs_driver: A string denoting the hdfs driver to use (if using a dataset on hdfs). Current choices are
          libhdfs (java through JNI) or libhdfs3 (C++)
      :param storage_options: Dict of kwargs forwarded to ``fsspec`` to initialize the filesystem.
      :param fileystem: the ``pyarrow.FileSystem`` to use.
      :return: A :class:`petastorm.unischema.Unischema` object
      """
      fs, path_or_paths = get_filesystem_and_path_or_paths(
          dataset_url_or_urls,
          hdfs_driver,
          storage_options=storage_options,
          filesystem=filesystem,
      )
  
      dataset = pq.ParquetDataset(
          path_or_paths,
          filesystem=fs,
          validate_schema=False,
          metadata_nthreads=10,
      )
  
      # Get a unischema stored in the dataset metadata.
      stored_schema = get_schema(dataset)
  
      return stored_schema
  
imports: import json
  import logging
  import os
  from concurrent import futures
  from contextlib import contextmanager
  from operator import attrgetter
  from urllib.parse import urlparse
  from packaging import version
  from pyarrow import parquet
  from six.moves import cPickle
  from petastorm import utils
  from petastorm.etl.legacy import depickle_legacy_package_name_compatible
  from petastorm.fs_utils import FilesystemResolver, get_filesystem_and_path_or_paths, get_dataset_path
  from petastorm.unischema import Unischema
label_desc: Use image node_id 11 for calling a global function with example usage: get_schema_from_dataset_url(dataset_url_or_urls, hdfs_driver, storage_options, filesystem) and returns: stored_schema